Means for forming channels in thermoplastic materials



Jan. 15, 1952 wlLuAms 2,582,368

MEANS FOR FORMING CHANNELS IN THERMOPLASTIC MATERIALS Filed March 17, 1949 CZZZOWZeyS- burred edges.

Patented Jan. 15, 1952 MEANS FOR FORMING CHANNELS 1N THERMOPLASTIC MATERIALS Paul A. Williams, West Seneca, N. Y., assignor to Glenn Confections, Ina, Buffalo, N. Y.

Application March 17, 1949, Seriai No. 81,894

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This invention relates to the formation of channels or grooves in thesurfaces of objects formed of thermo plastic materials. More particularly the invention relates to the manufacture of whistles oi thermo-plastic materials, such as of wax, paraffin or wax or paraffin-containing materials. Such whistles are commonly made by flush molding and are hollow.

An object of the invention is to provide an improved apparatus for forming channels in the surfaces of hollow articles of thermo-plastic materials, by which the channels may be formed more or less automatically and uniformly without imposing forces on the materials which might tend to tear or fracture them, or leave Another object of the invention is to provide an improved apparatus for making hollow whistles or similar objects of thermo-plastic materials; with which the whistle vent openings may be unifcrmiy formed without danger of tearing the relatively thin walls of the whistle shell, and without clogging any of the chambers or passages; and which will provide smooth and accurately formed edges at the whistle vent opening, sufficiently accurate to give uniform sounds when the whistle is blown.

A further object of the invention is to provide improved apparatus for accomplishing the above object and which will be somewhat automatic, ra' id an inexpensive.

Other objects and advantages will be apparent from the following description of one embodiment of the invention, and the novel features will be particularly pointed out hereinafter in connec tion with the appended. claims.

In the accompanying drawing:

1 is a plan of a portion of apparatus constructed in accordance with this invention for forming channel in whistles or other objects of thermo-plastic materials;

Fig. 2 is a transverse, sectional elevation through a mold in which hollow whistles are formed by flush molding, before the whistle vent openings are formed, and before the whistles are removed from the mold;

Fig. 3 is a transverse, sectional elevation through the apparatus shown in Fig. 1 the sec-.- ticn being taken approximately along the line 3-2 of Fig. l;

4 is another sectional elevation through the same, the section being taken approximately aicng the line ii, of Fig. 1;

Fig. 5 is a similar transverse sectional elevation through a portion of the same, the section being taken approximately along the line 5--5 of Fig. 1 after the whistle has reached the portion'of the apparatus at the section line 5-5; and

Fig. 6 is a side elevation of a flush molded whistle with a whistle vent formed in this manner.

In the illustrated embodiment of the invention, a hollow whistle I of suitable thermo-plastic materials or Waxes is shown in side elevation in Fig. 6 in completed form. These whistles are first molded without the whistle vent opening 2, in a mold of the type shown in Fig. 2. Referring to Fig. 2, the mold is formed of complemental mold sections 3 and 4 which abut face to face along a parting line 5, and there are a plurality of mold cavities 6 arranged side by side but slightly spaced apart in a row along the mold formed of the sections 3 and 4.

These mold sections have between them at the parting line, an opening 1 leading to each chambar in which a whistle is to be formed through which molding max in fluid condition may be introduced and excess removed as usual in flush molding, and flanges 8 and 9 extend along the sides of the mold at the face having opening 7, so that when the mold as shown in Fig. 2 is rotated clockwise a quarter revolution to bring the opening 1 uppermost, one may pour wax or other thermo-plastic material into the mold, and the flanges 8 and 3 act like a funnel to prevent spreading of the fluid wax. The heated wax congeals where it contacts the metal walls of the mold that define the whistle chamber. After the wax or thermo-plastic material has congealed, by cooling, to the desired thickness, the mold is inverted so that the uncongealed waxes or molding material may drain out, leaving the hollow shell that forms the whistle body. The mold sections 3 and 4 may then be separated, and since the larger part of the cavity is within the section 3, the molded shells will remain in the section 3, with the part thereof which was formerly in the molded section 4 projecting from the section 3. These whistle shells have a stem ill extending therefrom, which serves as a mouth piece, and this stem is provided with an air passage H, see Fig. 2 from end to end.

To form this air passage, a plate I 2 extends along and overlies themold sections 3 and l, as shown in Fig. 2, and tongues I3 extend therefrom into the mold chambers, one for each chamber, at the opening that molds the mouth piece. These tongues l3 are tapered toward their free ends so that after the wax or molding materials have congealed around them and the excess uncongealed molding material has been drained out, the plate 12 may be removed with its attached tongues 13 leaving the passages II. It will be observed from Fig. 2 that since the free ends of the tongues l3 project into the space of the molding chamber, the wax or molding material will congeal around the free ends, and as a result the inner ends of these air passages II will be closed. These closed ends of the air passages H are opened when the whistle sound openings are formed in accordance with the invention.

Referring next to Figs. 1, 3 and 4, I provide a frame !4 and in this frame I mount a pair of pulleys it (only one being shown), which are spaced apart along the frame. A pair of endless belts l6 and 11 pass around the pulleys i and are arranged side by side and spaced apart on the pulleys so as to provide a gap or space I8 between them. The upper runsor stretches of these belts It and H are generally horizontal and extend side by side, but spaced apart, and

travel at the same speed in the same direction. A rail 19 is disposed between the upper stretch oi the belt 16, and this run or stretch rides on the horizontal, upper face or surface of the rail It and is supported thereby from sagging. A similar rail 20 slidingly supports the upper stretch of the belt I? and prevents it from sagging.

The rails l9 and 2i; are supported respectively on studs 2| and 22 which pass through the frame it and are held in vertically adjusted positions by nuts 23 and 24, which are threaded on the studs 21 and 22 and engage opposite faces of the frame M, as shown in Fig. 3. Thus, these rails i9 and 26 may be separately adjusted vertically to diiferent heights and, consequently the heights of the belts l5 and Il in the upper runs or stretches may be determined. Inasmuch as the stem or mouth piece part of each molded whistle projects from mold sections a lot farther than the opposite side, the belt ll in its upper stretch is raised to a higher elevation, by its rail 28, than the belt l6, and this difference in levels of the belt stretches l5 and ll is maintained for a substantial distance. Disposed between the rails 19 and 29 is a steam pipe 25 which is supported on studs 28 that depend therefrom and pass through apertures in the frame id and are held at different adjusted positions in the frame 14 by nuts 21 and 28 that are threaded on the stud 25 and engage opposite faces of the frame M. This pipe 25 is connected at one end to a source of steam, not shown, so that this pipe 25 will be heated, athough other means of heating it, such as by an electric resistance, may be employed if desired. This pipe 25 is disposed approximately horizontally be tween the rails I9 and 20, so as to extend in the direction of travel of the belts.

Welded or otherwise secured on the pipe 25 is a fin or rib 29 which has an upwardly tapered, sharp edge, something like an inverted V in shape. This rib 29 runs lengthwise of the pipe 29 and is progressively higher towards one end, that is, it increases in height from the pipe 25 progressively in the direction of travel of the upper stretches of the belts It and IT. This rib or element 29 rises to progressively greater extents through the space between the belts in the direction of travel of the belts, for a purpose which will appear presently.

The rails l9 and 20 have upstanding, marginal guides or flanges 3D and 3!, disposed at intervals therealong, Fig. 4, which extend short distances along the sides of the belts resting on the rails, and prevent sidewise movements of the belts while on the rails. The frame I4 also has aguide arm 32 supported therefrom by arm 33. Ann 32 extends parallel to and above the rail I9, so as to serve as a placement guide for the mold section 3, as will be explained presently.

After a plurality of hollow whistles have been formed in the mold sections 3 and 4, as shown in Fig. 2, the plate I2 is first removed with its tongues l3, and then the mold section 4 is removed or separated, which leaves the hollow molded whistle shells extending somewhat from the sections 3, as shown in Fig. 4. lhe section 3 is then disposed, inverted, over the belts l6 and 11 with a side of the mold section 3 abutting against the guide rail 32, as shown in Fig. 3, and with the whistle shells resting on the belts i5 and ll, also shown in Fig. 3. The mold section 3 keeps the whistle shells properly positioned and spaced, and as it and the whistle shells are carried'along by the belts l6 and H, the lower end of the tapered apex or edge of the heated rib 29 will first engage with the whistle shells, because the rib gradually rises through the gap between the belts in the direction of travel of the belts.

As the whistle shells are carried along they will meet and engage with this heated rib 29. The movement is relatively slow, so that the rib may melt away the wax or molding material of the whistle shells with which it engages, and as the wax or molded material is melted by the heated rib 29, it drains away down the sides of the rib 29. The rib 29 will thus relatively rise into the moving whistle body and melt away an opening therein, as shown in Fig. 5, and in doing so, it forms the V-shaped whistle vent opening 2 in the molded whistle shell that opens into the chamber of the hollow whistle shell and also opens the inner end of the air passage 1 i. It also forms a sharp edge or corner 35 in the whistle shell, in proper position relatively to the air passage ll, so that an air column moving along the passage II into the whistle body will be set into vibration after it strikes the edge 35, as is well known in whistles. After the whistle shells have moved past the rib 29, the mold section 3 may be lifted and then the whistle shells removed from the mold section 3. They are then ready for use.

It will be observed that since the channels 2 are formed in the molded bodies in their lower faces, the melted wax or molding material will drain away and not plug the air passage ii. If one cuts the whistle opening with a cutter, it may leave on the cut edge a fuzzy or burr edge at the end of the air passage, that spoils the whistle sheet by causing improper and undesired eddy currents in the air column or stream. When the whistle vent opening is formed by melting, it gives a clean edge, free of burrs or fuzzy edges. Since the molded shell is above the heated rib that melts the channel therein, the wax which is melted will drain down the sides of the heated rib, because the heated rib keeps the wax that is in contact with it fluid, instead of forming ribs along the melted channel.

It will be understood that various changes in the details, materials and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. An apparatus for forming whistle vent openings in hollow whistle shells of thermo-plastic material and of the type having a sound chamher and a stem with an air passage leading towards said chamber, which comprises a pair of endless belts disposed with parallel, generally horizontal runs side by side but slightly spaced apart, on which a row of whistle shells may be supported in bridging relation between the said runs, and a rod disposed between said runs, extending lengthwise in the same direction as the runs, and having an upwardly convergent lengthwise rib between said runs, means for moving said belts at the same rate and in the same direction to carry said shells along and in contact with said rib, and means for heating said rib, said rib projecting above the faces of said belt runs an extent increasing progressively in the direction of travel of the belts so as to melt a whistle vent opening into said shells to progressively greater depths as they travel on the belts.

2. An apparatus for forming whistle vent openings in hollow whistle shells of thermo-plast ic material and of the type having a sound chamber and a stem with an air passage leading towards said chamber, which comprises a pair of endless belts disposed with parallel, generally horizontal runs side by side but slightly spaced apart, on which a row of whistle shells may be supported in bridging relation between the said runs, a support upon which each of said runs moves and which holds the runs from sagging, each support being vertically adjustable separately from the other, and a rod disposed between said runs, extending lengthwise in the same direction as the runs, and having an upwardly convergent lengthwise rib between said runs, means for moving said belts at the same rate and in the same direction to carry said shells along and in contact with said rib, and means for heating said rib, said rib projecting above the faces of said belt runs an extent increasing progressively in the direction of travel of the belts so as to melt a whistle vent opening into said shells to progressively greater depths as they travel on the belts.

3. Apparatus for forming channels in surfaces of hollow articles of thermo-plastic materials, which comprises a pair of endless belts having parallel, generally horizontal side by side runs, spaced apart, means for moving said belts in the same directions and speed, a support upon which each of said runs travels and by which the run is supported against sagging, and a heated rib disposed between said runs, with its length generally parallel to the direction of travel of said runs and rising progressively in the direction of travel of said runs to be engaged to increasingly greater extents with the bottom surfaces of said articles bridging and supported by said belts and conveyed bodily thereby in succession over and along said heated rib, whereby said rib will progressively melt a channel in each of said articles during their travel, and the melted material will drain away from said articles.

4. The apparatus substantially as set forth in claim 3, in which said rib is provided on a steam pipe to be heated thereby.

5. The apparatus substantially as set forth in claim 3, having guides along the edges of said runs to restrain said belt runs from sidewise movement during their travel, and a guide above and to one side of one of said runs against which said articles may be placed when deposited on said runs to determine the position of the articles and hence the positions of the channels melted therein.

PAUL A. WILLIAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,049,412 Bauer Aug. 4, 1936 2,348,591 Bailey May 9, 1944 2,428,174 Morin Sept. 30, 1947 2,450,448 Sawyer Oct. 5, 1948 

